AstronomyandAstrology

Differences : Origins : Assumptions

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Definitions

Astronomy is a science. It is the study of the objects in the Universe. Stars, planets and comets are
examined to determine their structure and origin. As a science it has links with other sciences like mathematics, physics and chemistry.
Astronomy treats the Earth as one of millions of bodies in the Universe.

Astrology is a belief system. The belief is that the positions of the Sun, Moon and planets against the
starry background influences peoples' personalities and shapes their lives. An implicit assumption is that the Earth is a special part of the
Universe.

This essay discusses these two differing subjects.

The Planets and The Zodiac

Astrologers deal with the positions of the planets against the starry background. Astrologers will say Mars is in
Virgo therefore this will happen or that will happen. The basis of astrology is the position of the Sun, the Moon and the five naked
eye planets against the patterns formed by the stars. These patterns are called
Constellations. The Sun, Moon and planets are all labelled as planets by
astrologers. This is in line with the original meaning of the word as "wanderers".

The Sun and Moon appear larger than the other planets so their influence is larger. The five planets have differing properties.

Venus is a brilliant white object in the sky and is named after the Roman goddess of beauty.

Mercury is silvery white and moves around the Sun quickly. It is seen as the messenger of the gods.

Mars is red in colour. Since this the colour of blood, Mars is considered to be the god of war.

Jupiter is the king of the gods because it spends a year in each zodiac constellation.

Saturn is the baleful planet because of its relative faintness, its pale yellow colour and its slow movement amongst the stars.

Each constellation has a planet associated with it. Astrologers will say something like Taurus is ruled by
Venus. Astrology is based on birth charts for an individual. The position of the Sun, Moon and planets is plotted on the zodiac at the
moment of birth. The constellations that are rising and setting are also listed. The astrologer will then use this information to determine the
personality and attributes of the individual.

In actual fact, the constellations are artificial areas in the sky invented originally by humans. They are
based on star patterns visible from Earth. All the stars in a constellation are scattered at random in space. The patterns have no real
significance. Each culture uses its own patterns. Where the West uses names like The Bull and
The Scorpion, the Chinese use The Rat or The
Snake. The constellations are still used by astronomers because they are convenient. It is easier to say that
Mars is in Virgo than to say Mars has coordinates -5 degrees South, 177 degrees
West.

Most constellations do not even resemble the animal or person they are named after. This is an example below:

Can you recognise the shape? It is actually Aquarius. None of these stars are close together in space or
related to each other or similar to each other. It is human imagination that associates water with this group of stars.

Here is an example of a constellation that does have a resemblance to the animal it represents:

This is Leo. With a bit of imagination you can imagine a male lion sitting on the ground with its maine.
This constellation was named by the Grreks who saw it as an animal they were familiar with. Lions were then common in Asia as well as
Africa.

But wait.

The above image is as it appears from the Northern Hemisphere. For observers in the Southern Hemisphere it
would appear like the image below:

If a civilisation was observing from (say) Australia, this group of unrelated stars would not even resemble a lion. It looks more like a
boat. In addition there were no lions in Australia for it to be named after.

Constellations are not just human inventions - they are Northern Hemisphere biased. This makes astrology a cultural rather than a cosmological
activity.

The constellations have as much reality in the sky as the countries have on the Earth. They are used in a similar way. It is easier to say that
London is in England rather than London has a Latitude of 51 degrees North and a
Longitude of 0 degrees West.

Constellations, like countries, are human inventions.

Signs and Constellations

There is another point of confusion. The constellations that astronomers use to identify parts of the sky are not the same as the Zodiac signs
used by astrologers. The Zodiac signs were based on the constellations 2000 years ago when their modern (Latin) names were first used. The Signs
are an astrological convenience ignoring the differences between two different types of solar calendar. This is described further in
The Calendar.

The astrological signs are about a month out from the astronomical constellations. When an astrologer says the Sun is
in Cancer, an astronomer will look for the Sun in Gemini.

If Mars is in Virgo, astronomically it means that, if you look at the group of stars known to the Western cultures as Virgo, you will see an extra red star-like object amongst those stars. That will be Mars. However when an astrologer says that Mars in is Virgo, he is talking about the abstract astrological sign that has no physical significance. Mars will actually be in Leo.

The difference in the two solar calendars is caused by an astronomical phenomenon called
precession.

An astrologer would make predictions based on the position of Mars in an imaginary sign. An astronomer would be able to point out Mars; it would
be found amongst the stars of Leo.

Moden mobile (cell) phone Apps like GoogleSky allow users to point to the Sun and see which stars it is close
to. Anyone can do that and compare to where astrological dates say the Sun should be. Because astrology is more akin to a religous belief, even
evidence like this would normally be ignored.

But even to say Mars is IN Leo is incorrect. Mars would be in the same direction as the stars of Leo. These
are themselves at different distances. It is a bit like holding a hand against a building saying the hand is
IN the the building.

The brightest star of Leo is called Regulus (a Latin word meaning "ruler"). In 2012, the planet Mars could be
seen very close to this star. However they were not really close together. Light from Mars was taking less that five minutes to
reach the Earth, while the light from Regulus required 77 years.

Mars is said to be the god of war because its red colour reminded the ancients of blood. Mars is red because
its surface is covered with iron oxides - rust! Also, the constellations in use by the West are not the same as those used by other cultures.
The Chinese and Indians have totally different zodiac signs as well as different numbers of signs of the zodiac. Remember,

the signs of the zodiac are created by humans and do not exist in the Universe.

Astrologers invented the signs of the zodiac (as distinct from the constellations) after the effects of precession became generally known. If
the constellations can be likened to the Earth's countries (France, USA, Namibia) then the signs of the Zodiac can be likened to ancient
kingdoms that no longer exist (Babylonia, Ottoman Empire, Phoenicia). Each Zodiac sign is 30 degrees wide in the sky. This is how astrologers
have defined them. The astronomical constellations are all of different sizes, much like countries on the Earth.

Some astrologers will say that a particular zodiac sign represents the essence of a particular time of year,
much like a seasonal effect. But each hemisphere of the Earth has different seasons at the same time of year. Some areas of the Earth have four
seasons (Spring, Summer, Autumn, Winter) while other areas have two (Wet, Dry).

The stars do not cause the seasons. They are convenient markers for the apparent path of the Sun around the starry sky. I say
apparent because the Sun's movement through the zodiac is really due to the Earth moving around the Sun.

The seasons are caused by the Earth's equator being tilted by 23 and a half degrees from the plane of the
Earth's orbit around the Sun.

On 21st June the Northern hemisphere passes through the Summer Solstice. 2000 years ago the Sun would have
been in front of the stars that we call Cancer at this solstice. Hence the Tropic
of Cancer. In fact at this solstice now the sun would be in Gemini. If a Total Eclipse of the Sun
were to occur at the solstice, the stars of Gemini would be visible around or
near the sun.

In astrology, a person's "star sign" is one of the 12 zodiac signs that the Sun is in on the birth date. The dates for the Sun's passage through
each sign are well known.

In astronomy, the Sun actually passes through 13 constellations in the sky. The table below lists the actual dates that the Sun is within these
constellations in the early 21st century, beginning with Spring in the Northern Hemisphere. All seasonal notes are for the Northern Hemisphere.
The dates will change by one day every 70 years.

Incidentally, the word zodiac means circle of animals in Greek.

Constellation

Common Name

StartDate

EndDate

Notes

Pisces

The Fishes

12 Mar

18 Apr

The Northern Hemisphere Spring Equinox occurs when the Sun is in this constellation (20 to 22 March).

Originated in Babylonia and formed
from the combination of two earlier constellations. Very faint stars. In China it is three constellations including a house and marshes.

Aries

The Ram

18 Apr

14 May

Originally Greek (the ram with the golden fleece). It features a line of three stars.

2000 years ago, the Spring Equinox occured when the Sun
was in this constellation.

It was a prince to the Assyrians. To the Babylonians it was a farm hand. It became a ram after the animal begun to be
sacrificed at this time of year.

In China it is a pair of inspectors. In the Marshall Islands it is a porpoise. In ancient Egypt this part
of the sky was associated with the god Amun-Ra. To the Chinese it was several constellations including a sickle. To the Hebrews it was Simeon.

Taurus

The Bull

14 May

21 Jun

Known to the Minoans, Egyptians, Hebrews and Mesopotamia. To the Grreks it was the god, Zeus, in bull form in order to abduct a Phoenician princess.

It is a very prominant constellation with two bright star clusters: The Pleiades (or Seven Sisters) and The Hyades. Its brightest star is
Aldebaran ("eye of the bull" in Arabic).

The bull and seven sisters appear on cave paintings in France dating back 15,000 years. For many
Australian peoples, the Pleiades was the Seven Fishermen in a boat.

Gemini

The Twins

21 Jun

20 Jul

The Twins, Castor and Pollux. To the Greeks they were sons of Zeus: one was immortal and the other wasn't.

The Northern Hemisphere Summer
Solstice occurs when the Sun is in Gemini (21 to 22 June). The Northern tropic should now really be called the Tropic of Gemini.

This is a
prominant constellation above Orion.

In China it is two constellations: The White Tiger and the Vermillion Bird. In India it was the Two
Chariots.

Both Uranus (1781) and Pluto (1930) were discovered among the stars of Gemini.

Cancer

The Crab

20 Jul

10 Aug

A small dim constellation with a pretty star cluster, Praesepe (The Beehive). It occurs in the story of the Greek hero, Hercules.

To the Akkadians it was known as the Northern Gate of the Sun. The Egyptians identified it with the god, Anubis. In China it is part of
the Vermillion Bird.

Leo

The Lion

10 Aug

16 Sept

A large distinctive constellation. It also occurs in the story of Hercules. Its brightest star is Regulus (Latin for "ruler"). It has been
depicted as a lion in many Northern Hemisphere cultures going back 6000 years.

Virgo

The Virgin

16 Sept

31 Oct

The largest constellation of the zodiac. To the Greeks it was Demeter, the corn goddess. Its brightest star is Spica (Latin for "ear of corn").

The Northern Hemisphere Autumnal Equinox occurs when the Sun is in Virgo (22 to 23 September).

To the Babylonians it was the Furrow and was
associated with agriculture.

Libra

The Scales

31 Oct

23 Nov

A small, faint constellation.

Originally it was the claws of the scorpion but the Romans changed it to a balance or scales because the
Autumn Equinox (when the days and nights are equal in length) occured with the Sun in this part of the sky 2000 years ago. It is the only
non-living zodiac constellation.

In India it was known as the Hand.

Scorpius

The Scorpion

23 Nov

29 Nov

To the Greeks, this is the scorpion that killed Orion, the Hunter. In the sky, Scorpius rises as Orion sets so the two are never visible
together.

It is a spectacular constellation, especially from the tropics or the southern hemisphere and one of the few that resembles the
animal it is named after. Its brightest star is Antares, Greek for "rival of Mars" because of its prominant red colour.

To the people of
Java the constellation is called the Brooded Swan. For the Guringai people of Australia, this was part of a large constellation called the
Emu.

The name, Scorpio, is only used by astrolgers.

Ophiuchus

The Serpent Bearer

29 Nov

18 Dec

This is the Greek god of medicine, Asclepius, who is depicted holding a serpent, a traditional symbol for healing.

This region of the sky
contains many star clusters, the Milky Way and Barnard's Star, the nearest star to the Earth in a Zodiac constellation.

Although the Sun passes
through this constellation it is ignored by astrologers.

To the Babylonians it was Nirah, a serpant god.

Sagittarius

The Archer

18 Dec

19 Jan

This is Crosus, son of the Greek god, Pan, and the inventor of archery.

This part of the sky contains the brightest portion of the
Milky Way as it looks towards the centre of our Galaxy. It is not well seen from the Northern Hemisphere.

The Northern Winter Solstice occurs
with the Sun in this constellation (20 to 22 December). The Southern tropic should now be called the Tropic of Sagittarius.

To the Babylonians
it was the centaur-like god, Nerigal.

Capricornus

The Sea Goat

19 Jan

16 Feb

A small dim constellation. It originated in Babylonia as a "goat-fish".

In 1846 the planet Neptune was discovered in this part of the sky after predictions by mathematicians who had studied orbital irregularities
in the movement of Uranus.

In China it was the Black Tortoise. The Nakh people of the Caucuses called this region of the sky the Roofing
Towers. In the South Pacific, it was called the Cavern of Parental Yearnings

Aquarius

The Water Bearer

16 Feb

11 Mar

Another dim constellation originating in Babylonia. At that time it was the rainy season when the Sun passed through this part of the sky.
It was associated with the god Ea who is depicted holding a vase of water. The constellation was previously a goose and a peacock.

In China it was the Army of Yu-Lin.

Assumptions

Astrology is based on a number of assumptions that have been discredited in the last 2000 or so years. It was formulated when the sky was thought
to be a crystal sphere centred on the Earth with the stars placed on this sphere. The stars and planets were thought to be gods in orbit around
the Earth. The Earth was thought to be the centre of the Universe. The Earth was made of four so-called
elements (earth, fire, air and water) while the heavens were made of a fifth element, the
aether. This was the basis on which astrology was formulated.

We now know that the Earth is one of eight major planets in orbit around the Sun which is itself an ordinary star no different to the other stars
in the sky (except closer). We also know that there are more than four elements (closer to 100, see
The Elements). More
importantly we know that the stars and planets are made up of the same elements that we find on Earth. We
are PART of the Universe.

In the past there was no difference between astrology and astronomy. The two grew up together in a world of spirits, gods, ghosts and mysticism.
Many people believe that the ancients had knowledge that has been lost. Some ancient ideas were remarkably accurate. Others were totally wrong.
There are many examples of this. Below are tables showing a selection of ideas by two Greek scientists Aristotle and Pythagoras. Correct ideas
are marked by a green tick ("check" in USA); incorrect ideas are marked with a red cross.

Aristotle's Ideas

Dolphins are mammals

The earth is the centre of the solar system

Objects of different weight fall to the ground at different speeds

The brain is an organ for cooling the blood

The heart is the centre of emotion

Matter is made of four elements

Pythagoras' Ideas

The properties of right angled triangle

The square root of 2 can not be written as a fraction

There are only five planets because there are only five regular
geometric solids

The Scientific Method

Only by observing nature can an idea be verified or not. You cannot use the fact that something was believed by the ancients to verify an idea.
You cannot say that something is correct because lots of people believe it. For most of history people believed the earth was flat! You cannot
say that something is true because a famous scientist believes it. Isaac Newton discovered the laws of
gravity (correct) and also wrote books about angels. You cannot say that angels exist because a genius like Newton believed in them. You cannot
say the laws of gravity are correct because Newton says so. The laws of gravity are verified by observing objects travelling under the force of
gravity and seeing if their paths are the ones predicted by these laws. There is no other way.

Albert Einstein's
Relativity Theory is considered one of the greatest achievements of human thought - but he did not accept many of the results of
Quantum Mechanics, the other pillar of 20th century science. You cannot say whether Quantum Mechanics is true by quoting Einstein's dislike of it. Only nature can answer the question is this theory correct.

It is important to separate cause and effect. People once noticed that when the Moon was visible, plants died. People believed that moonlight was harmful to plants. In fact it isn't. When the Moon is visible, the sky is clear. When the sky is clear, frost is more likely in the Temperate regions. It is the frost that kills the plants NOT the moonlight.

The clear sky (cause) produces frost (effect) which kills plants and also makes the Moon visible (effect). The dead plants and the Moon are both the effects of the clear sky. The Moon and the dead plants are not directly related. Much of astrology is based on this type of reasoning.

For all life on earth the Sun is the most important object in the sky. It does not follow that the planets influence the Earth or us.

Some astrologers use tides as an explanation for astrology. The argument is as follows:

The Moon causes tides (correct).

Tides are a pull on the Earth's waters (almost true but not quite right).

The human brain is mainly water (correct).

Therefore the Moon affects the brain.

This argument only sounds good if the listener does not fully understand how tides work. The tidal force of the Moon on the Earth depends on the mass of the Moon and its distance from the Earth. It also depends on the width of the Earth. Remember there are TWO tides per day. So it cannot be just that the Moon is pulling the Earth. The width of the Earth compared to the distance between the Earth and Moon is much much larger than the width of a human compared to that distance. This is difficult to envisage but is mathematically sound.

Astronomy is based on the scientific method of observation, deduction and experiment. Astrology is not. All experiments performed on astrology are inconclusive at best, and disprove it at worst. Astronomy is a science that can make verifiable predictions. Astrology's predictions are hit and miss. In fact you get the same results as chance.

How humanity came from believing Creation Myths to postulating the Inflationary Big Bang Theory. The key stages in our understanding of our place in the cosmos and the people who broadened our understanding.